Loading...
Search for:
machining-process
0.012 seconds
Variation source identification of multistage manufacturing processes through discriminant analysis and stream of variation methodology: A case study in automotive industry
, Article Journal of Engineering Research ; Volume 3, Issue 2 , July , 2015 , Pages 96-108 ; 23071885 (ISSN) ; Baradaran Kazemzadeh, R ; Akhavan Niaki, S. T ; Sharif University of Technology
University of Kuwait
2015
Abstract
Product quality problem is a critical issue for multistage manufacturing processes, especially in continuous production lines whereby quality characteristics are measured at the end of the line. Therefore, it is important to reduce process variation by identifying its sources and eliminating its causes. In this regard, a novel approach, to identify the source of variation in multistage manufacturing processes through integration of the Fisher's linear discriminant analysis and the stream of variation methodology, is proposed. Linear discriminant analysis is used to separate the variation of quality characteristics through the different stages of the manufacturing processes while the stream...
Numerical Simulation of Laser Assisted Machining of Hard-to-Machine Alloys
,
M.Sc. Thesis
Sharif University of Technology
;
Movahhedy, Mohammad Reza
(Supervisor)
;
Akbari, Javad
(Supervisor)
Abstract
Laser Assisted Machining is a novel type of machining in which laser beam warms up the workpiece locally. Using laser beam in machining leads to a reduction in machining forces, an increase in tool life and an improvement in surface quality. This study introduces the process, reviews literatures related to it and then, simulates the process thermo-mechanically. A process in which a Gaussian pulsed ND-YAG laser beam of 700w power is used for machining of AISI 52100 is simulated, considering sufficient properties of material. Simulations are done using Abaqus®/Standard and Abaqus®/Explicit softwares. Also, Abaqus®/CAE visual interface, Intel® Visual Fortran compiler alongside with Microsoft...
Active Vibration Control of Constrained Industrial Manipulators Using Piezoelectric Actuator
, M.Sc. Thesis Sharif University of Technology ; Vossoughi, Gholamreza (Supervisor) ; Boroushaki, Mehrdad (Supervisor)
Abstract
Nowadays, due to the advancement of robotic technologies and development of industrial robots, the robot manipulators are widely used for automation of various manufacturing processes, such as finishing processes. In these applications, the contact has to be made between robot end-effector and environment. Therefore, control of interaction force in the constrained manipulators is an important demand. On the other hand, due to use of gear box and belts for energy transmission in robot joints, robot manipulators have flexible joints. The vibration, generated due to the interaction force and robot joint flexibility, can deteriorate surface roughness in automated finishing processes. In order to...
Finite element simulation of ultrasonic-assisted machining: a review
, Article International Journal of Advanced Manufacturing Technology ; Volume 116, Issue 9-10 , 2021 , Pages 2777-2796 ; 02683768 (ISSN) ; Akbari, J ; Sharif University of Technology
Springer Science and Business Media Deutschland GmbH
2021
Abstract
Ultrasonic-assisted machining is an advanced method which could improve the process of machining. Besides, simulation modeling process is a method to help the researchers analyze different aspects of the process with more details in a shorter time. Simulation of ultrasonic-assisted machining is also a field of research that is of interest to researchers working in the field of machining processes. In recent years, a variety of papers have been published where cutting forces, chip formation, tool wear and temperature, and microstructure changes were simulated. That being the case, a review paper is required to represent the advances implemented by researchers in the simulation of...
Fault diagnosis within multistage machining processes using linear discriminant analysis: a case study in automotive industry
, Article Quality Technology and Quantitative Management ; Volume 14, Issue 2 , 2017 , Pages 129-141 ; 16843703 (ISSN) ; Baradaran Kazemzadeh, R ; Akhavan Niaki, S. T ; Sharif University of Technology
Taylor and Francis Ltd
2017
Abstract
Statistical process control provides useful tools to improve the quality of multistage machining processes, specifically in continuous manufacturing lines, where product characteristics are measured at the final station. In order to reduce process errors, variation source identification has been widely applied in machining processes. Although statistical estimation and pattern matching-based methods have been utilized to monitor and diagnose machining processes, most of these methods focus on stage-by-stage inspection using complex models and patterns. However, because of the existence of high rate alarms and the complexity of the machining processes, a surrogate modelling is needed to solve...
Prediction of Machining Chatter Based on 2 Dimensional FE Dynamic Modeling of Chip Formation
, M.Sc. Thesis Sharif University of Technology ; Movahhedi, Mohammad Reza (Supervisor)
Abstract
In machining processes, chip formation is one of the most important methods to obtain the final shape of a work-piece. Improving the machining processes leads to the increase in the material removal rate (MRR) and reduction of high economical costs. Vibration is an undesirable phenomenon in machining processes because it results in reduction of material removal rate (MRR), poor surface finish and increased tool wear. Among various types of vibration, self-excited vibration or chatter is the most important one. It is obvious from previous investigations that for prediction of machine tools vibration, many simplifications were assumed while the linear and non-linear effects are not considered...
Propose a Model to Minimize Energy Consumption in Turning Machining Operations
, M.Sc. Thesis Sharif University of Technology ; Fatahi-Valilai, Omid (Supervisor)Integration of Design and Manufacturing Systems Using Neutral Data Structure
, Ph.D. Dissertation Sharif University of Technology ; Hooshmand, Mahmoud (Supervisor)
Abstract
In competitive environment of quick market changes, developing an interoperable manufacturing system is a necessity. Process planning as a connection link between design and manufacturing, has never been able to integrate these up/down stream activities and in spite of employing computer systems, CAPP’s information has been managed in an isolated manner. To realize interoperability, the exchange of part and product data must be independent of their platforms. There are two basic approaches for this purpose: i) Utilizing interface and ii) Utilizing neutral formats. STEP (Standard for the Exchange of Product data) plays a significant role as a neutral data model to integrate design,...
Ultrasonic-assisted grinding of Ti6Al4V alloy
, Article Procedia CIRP ; Volume 1, Issue 1 , 2012 , Pages 353-358 ; 22128271 (ISSN) ; Movahhedy, M. R ; Akbari, J ; Sharif University of Technology
2012
Abstract
In conventional grinding of hard to cut materials such as Ti6Al4V alloys, surface burning, redeposition and adhesion of chips to the grinding wheel and workpeice occur visibly unless it is carried out at low speeds and with high volume of cutting fluid. Ultrasonic assisted grinding is an efficient machining process which improves the machinability of hard-to-cut materials by changing the kinematics of the process. In this research, the effect of imposition of ultrasonic vibration on the grinding of Ti6Al4V alloy is studied. Longitudinal vibration at ultrasonic frequency range (20 kHz) is applied on the workpiece and machining forces and surface roughness are compared between conventional...
Investigation of thermal effects on machining chatter using FEM simulation of chip formation
, Article Procedia CIRP ; Volume 1, Issue 1 , 2012 , Pages 50-55 ; 22128271 (ISSN) ; Movahhedy, M. R ; Sharif University of Technology
2012
Abstract
Chatter vibration is a major cause of limitations in increasing material removal rate in machining. Machining chatter is caused by the interaction between tool and work-piece. Various nonlinear phenomena in the machining process affect the occurrence of chatter. Finite element simulation of chip formation allows for incorporation of various factors in the chip formation process. It can therefore be used to simulate the occurrence of chatter in practical conditions and to predict the conditions that lead to stable cutting. In this paper, a one degree of freedom dynamic model of the cutting tool is used to simulate the interaction of machining dynamics with the thermo-mechanical chip formation...
Tool condition monitoring based on sound and vibration analysis and wavelet packet decomposition
, Article 2012 8th International Symposium on Mechatronics and its Applications, ISMA ; April , 2012 ; 9781467308625 (ISBN) ; Akbari, J ; Behzad, M ; EMAL(Emirates Aluminium) ; Sharif University of Technology
2012
Abstract
Tool Condition Monitoring (TCM) is a vital demand of advanced manufacturing in order to develop automated unmanned production. Continuing the machining operation with a worn or damaged tool will result in damages to the workpiece. This problem becomes more important in supplementary machining processes like drilling which the workpiece usually has passed a lot of machining processes and any damage to workpiece at this stage results in high production losses. In this research features of sound pressure and vibration signals in drilling process are recorded and analyzed in order to detect tool wear. Signal statistical features are extracted in time domain, and the features trends as the tool...
Spindle speed variation for regenerative chatter suppression in turning process with tool wear effect
, Article ASME 2010 10th Biennial Conference on Engineering Systems Design and Analysis, ESDA2010, 12 July 2010 through 14 July 2010 ; Volume 4 , 2010 , Pages 619-626 ; 9780791849187 (ISBN) ; Vossoughi, G ; Rahaeifard, M ; Movahhedy, M ; ASME Turkey Section ; Sharif University of Technology
Abstract
Chatter suppression in machining processes results in more material removal rate, high precision and surface quality. In this paper, a single degree of freedom model of orthogonal turning process is used to set up the delay differential equation of motion with considering the tool wear effect as a contact force between the workpiece and tool flank surfaces. Sinusoidal spindle speed variations with different frequencies around the mean speed are modulated to disturb the regenerative mechanism. The optimal amplitudes of the speed modulations are found based on a genetic algorithm such that the input energy to the turning process is minimized. Results of the stability analysis and the...
Spindle speed variation and adaptive force regulation to suppress regenerative chatter in the turning process
, Article Journal of Manufacturing Processes ; Volume 12, Issue 2 , August , 2010 , Pages 106-115 ; 15266125 (ISSN) ; Moradi, H ; Vossoughi, G ; Movahhedy, M. R ; Sharif University of Technology
2010
Abstract
Chatter suppression in machining processes results in more material removal rate, high precision and surface quality. In this paper, two control strategies are developed to suppress chatter vibration in the turning process including a worn tool. In the first stage, a sinusoidal spindle speed variation around the mean speed is modulated to disturb the regenerative mechanism. The optimal amplitudes of the speed modulations are found based on a genetic algorithm such that the input energy to the turning process is minimized. In the second stage, to improve the response of the system which is associated with small ripples under the steady state condition, an adaptive controller is designed. In...
Prediction of machining chatter based on FEM simulation of chip formation under dynamic conditions
, Article International Journal of Machine Tools and Manufacture ; Volume 50, Issue 7 , July , 2010 , Pages 611-620 ; 08906955 (ISSN) ; Movahhedy, M. R ; Sharif University of Technology
2010
Abstract
Machining chatter is an inherently nonlinear phenomenon that is affected by many parameters such as cutting conditions, tool geometry e.g., nose radius and clearance angle and frictional conditions at the tool/workpiece interface. Models for chatter prediction often ignore nonlinearities or introduce them through simple models for friction and geometry. In particular, the effect of chiptool interaction on the occurrence of chatter is not investigated thoroughly. This paper presents a novel approach for prediction of chatter vibration and for investigation of the effects of various conditions on the onset of chatter. This approach uses finite element simulation to investigate the...
In-process determination of laser beam absorption coefficient for laser-assisted turning processes
, Article International Journal of Advanced Manufacturing Technology ; Volume 92, Issue 5-8 , 2017 , Pages 2929-2938 ; 02683768 (ISSN) ; Movahhedy, M. R ; Ahmadian, M. T ; Razavi, R. S ; Sharif University of Technology
Abstract
Modeling of the laser-assisted machining (LAM) process requires an accurate estimate of the surface absorption coefficient. In addition to the laser type and material properties, this parameter is dependent on the state of the process in terms of surface quality, texture, oxidation state, and temperature change during the machining process. In this article, two methods are presented for calculating this coefficient based on the surface temperature obtained from measurement by a pyrometer and an analytical model of the process. In the first method, the pyrometer is fixed on a lathe bed while in the second method, a co-moving pyrometer is used. Temperature measurements in both methods are...
Modeling and active control of chatter vibrations of piezoelectric stacked machining arm in micro-turning process
, Article Meccanica ; Volume 55, Issue 9 , 18 July , 2020 , Pages 1707-1731 ; Moradi, H ; Movahhedy, M. R ; Sharif University of Technology
Springer
2020
Abstract
Self-excited vibrations known as chatter are considered as the most detrimental issue in micro-turning processes. Occurring unpredictably, they adversely affect the tool life, productivity rate and surface quality of the machining processes. In this paper, a novel machining arm is modeled as a piezoelectric stacked rod which is subjected to a chatter force in the orthogonal micro-turning process. Due to the fact that machining processes are affected by various sources of uncertainties, H∞ robust control approach is used to suppress the chatter vibrations of the machining arm in the presence of tool wear and dynamic model parameter variations. Also, input control force of the system is...
Adaptive control of regenerative chatter in turning process with tool wear effect
, Article ASME International Mechanical Engineering Congress and Exposition, Proceedings ; Vol. 10, Issue PART B , 2010 , pp. 1023-1030 ; ISBN: 9780791843833 ; Moradi, H ; Vossoughi, G. R ; Alasty, A ; Movahhedi, M. R ; Sharif University of Technology
Abstract
Chatter suppression is of great importance for achieving high precision and surface quality in machining processes. A single degree of freedom model of orthogonal turning process is used to set up the nonlinear delay differential equation of motion. Tool wear effect is considered as the contact force between the workpiece and tool flank surfaces. Uncertainties in parameters of dynamic model and machining conditions are included in the model. An adaptive control strategy is applied for chatter suppression in cutting process. The force provided by a piezoactuator is the control input of the system. Results of stability analysis and adaptive control for two distinct cases of sharp and worn...
A modular extreme learning machine with linguistic interpreter and accelerated chaotic distributor for evaluating the safety of robot maneuvers in laparoscopic surgery
, Article Neurocomputing ; Volume 151, Issue P2 , March , 2015 , Pages 913-932 ; 09252312 (ISSN) ; Behzadipour, S ; Sharif University of Technology
Elsevier
2015
Abstract
In this investigation, a systematic sequential intelligent system is proposed to provide the surgeon with an estimation of the state of the tool-tissue interaction force in laparoscopic surgery. To train the proposed intelligent system, a 3D model of an in vivo porcine liver was built for different probing tasks. To capture the required knowledge, three different geometric features, i.e. Y displacement of the nodes on the upper surface and slopes on the closest node to the deforming area of the upper edge in both X-. Y and Z-. Y planes, were extracted experimentally. The numerical simulations are conducted in three independent successive stages. At the first step, a well-known...
Adaptive control of regenerative chatter in turning process with tool wear effect
, Article ASME International Mechanical Engineering Congress and Exposition, Proceedings ; Volume 10, Issue PART B , 2010 , Pages 1023-1030 ; 9780791843833 (ISBN) ; Moradi, H ; Vossoughi, G. R ; Alasty, A ; Movahhedi, M. R
Abstract
Chatter suppression is of great importance for achieving high precision and surface quality in machining processes. A single degree of freedom model of orthogonal turning process is used to set up the nonlinear delay differential equation of motion. Tool wear effect is considered as the contact force between the workpiece and tool flank surfaces. Uncertainties in parameters of dynamic model and machining conditions are included in the model. An adaptive control strategy is applied for chatter suppression in cutting process. The force provided by a piezoactuator is the control input of the system. Results of stability analysis and adaptive control for two distinct cases of sharp and worn...